1. Field of the Invention
This invention relates to method and apparatus for displaying relative wind information to an aircraft pilot or co-pilot. The displayed wind information preferably includes wind speed and wind direction, head wind or tail wind components thereof and left or right correction angles for steering the aircraft accurately across a desired ground track in spite of the prevailing winds aloft encountered relative to the aircraft.
2. Description of the Prior Art
The following prior art issued US patents are examples of prior art aircraft instrumentation for depicting relative wind information:
Arguably also of relevance are patents such as the following even though they are not directed to displays of wind information:
Tooze uses a small microprocessor driven array of LEDs and suggests that his display might be overlaid with other primary aircraft cockpit displays and the like. However, Tooze does not appear to suggest that the microprocessor might be on the same PCB with the LED arrayxe2x80x94and certainly has no suggestion of a two-wire power/data interface nor any wind information display and certainly not the unique display format of the exemplary embodiment described herein below.
Beadle provides a digital LED display to be overlaid with a conventional cockpit instrument. However, the display format is entirely different from the present invention, has nothing to do with wind information, does not in any way suggest the use of a small microprocessor mounted on the same PCB as the LED array, does not in any way suggest a simple two-wire power/data interface, etc.
The generation of raw wind direction, speed, component, drift correction or display brightness data is already available (or can be conventionally made available) in serial form (e.g., a xe2x80x9cTAS 1000 Air Dataxe2x80x9d computer available from Insight Avionics Inc., Box 122, Fort Erie, Ontario L2A 5M4, Canada).
The exemplary embodiment of this invention provides a small, thin, lightweight printed circuit board display having its own onboard microprocessor and LED array driven directly by the microprocessor. Both data and power can be conveyed over a single two-wire circuit (e.g., plus five volts, ground). Short interruptions in the power supply are interpreted as the serial data stream (different interruption durations representing a start data pulse, a data xe2x80x9c0xe2x80x9d pulse and a data xe2x80x9c1xe2x80x9d pulse). Even a very slow data rate (e.g., 20 bits per second) suffices to update the display of wind direction, wind speed, wind component, drift correction and display brightness (e.g., every 1.6 seconds when air data computer output is updated).
This simple two-wire combined power/data interface permits a very small interconnect ribbon to be the only interconnection of the PC board display unit to the driving apparatus. The small lightweight PCB (e.g., only 1.3 inches in diameter in the prototype) in a suitable housing may literally be glued or otherwise affixed onto the instrument panel (including even the face of another instrument) so as to literally require zero additional panel space in the aircraft. Such a ribbon two-wire connector may use conductors so small as to be substantially transparent. If desired, additional information (such as the output from an altitude encoder or error correction codes or the like) can be added to the bit stream.
The exemplary display format depicts wind direction in 15xc2x0 increments around an outer circumference. Wind speed is shown as a second smaller circumference circular bar graph while the xe2x80x9cdriftxe2x80x9d (i.e., the required steering crab angle to counteract the cross-wind component) is displayed as a horizontal bar graph to the right or left of center indicating corresponding wind correction angle to the left or right. The longitudinal head wind or tail wind component is also preferably displayed as a blinking (or missing) bar in the midst of the wind speed display. There are many possible variations in the display format. For example, some of the graphic displays could be replaced with numeric read-out displays
In the exemplary embodiment, an aircraft wind indicator is provided by disposing wind display elements on one side of a printed circuit board while wind data processing and display driving circuits are disposed on the other side of the printed circuit board.
In the exemplary embodiment, the wind indicator is disposed in a housing of about 1.3 inches diameter with an adhesive pad on its backside for affixation to an aircraft instrument panel.
If desired, a two-conductor ribbon cable having a substantially transparent base may be used for simultaneously conducting both power and data to the indicator circuits. In this manner, the indicator housing itself may be affixed to the instrument panel in any desired location (even on the face of some other existing instrument such as in the center of an altimeter) without providing any substantial visual obstruction by the interconnecting electrical umbilical cable.
Preferably, the display elements are disposed so as to depict wind speed, wind direction and wind correction angle data. The display elements may be solid state LCD elements, digital numeric displays or light emitting elements such as light emitting diodes or the like. In the preferred exemplary embodiment, display elements are arrayed in two concentric circular tracks (for depicting wind direction and wind speed respectively) and in an linear track (for depicting left and right wind correction angles by bar graphs extending to the left or right of a central reference indicia). The magnitude of the head or tail wind component may be indicated by a blanked (or blinked) display element along the bar graph depicting the velocity of the winds aloft being encountered by the aircraft.
In another aspect, the exemplary embodiment of the aircraft wind indicator may merely include visible indicators disposed to display wind speed, wind direction and wind correction angle together with data processing and indicator driving circuits connected to drive such visible indicators in accordance with digital data representing such wind speed, wind direction and wind correction angle information. In the exemplary embodiment, the visible indicators include solid state light emitting elements arrayed on one side of a printed circuit board and data processing and indicator driving circuits disposed on the other side of the same printed circuit board. A translucent or transparent substrate may be imprinted with graphical symbols and aligned with light emitting elements that are selectively activated so as to display graphical depictions of such wind data.
In the exemplary embodiment, the indicator includes a serial data input port to data processing and light source driving circuits which, in turn, drive three respective arrays of controllable discrete light sources arranged to graphically depict wind direction, wind speed and wind correction angle data. A pair of electrical conductors may be used for supplying power to the indicator and data as well when represented by short coded interruptions in the power supply that can be interrupted to represent data such as xe2x80x9cstartxe2x80x9d and digital xe2x80x9c0xe2x80x9d and digital xe2x80x9c1xe2x80x9d values. Although light emitting diodes are used in the presently preferred exemplary embodiment, other sources of display technology (e.g., liquid crystal display, cathode ray tube, plasma display, mechanical pointers, and the like) may also be used.